Sue are you talking about switches actually on the heater? If so sorry I cant help.
Or are you talking about the two main switches under the seating?
Have you tried both electic and gas?
On my Fleetwood One would be the electric switch (a bit bigger than a household light switch)
The other would be the gas and temperture switch, it would be dome shaped with the gas ignition on the outer ring
If you use the gas the dome switch should light up green if after a few seconds it goes red, switch off and leave for 5 minutes and try again, if it goes red again the problem would be to technical for me to give you an answer
Hope this helps.